1. Field Of The Invention
The present invention relates to a machine for the multiple-pass dyeing of cord fabrics.
2. Discussion of Background
A number of different solutions have been developed in the field of cord fabric dyeing machines. In fact, the machines known to this date show drawbacks related both to their treating speed and their construction, which must be capable of inducing the fabric to absorb an optimum amount of color so as to achieve a uniform dyeing result.
Considerable progress was achieved thanks to the machine built according to the Italian patent application No. MI93A 01474 (hereinafter "the 474 application") of Jul. 8, 1993, which attempted to provide a solution for the problems encountered up to that point. The contents of the '474 application are incorporated herein by reference.
The '474 application notes that the machine is formed by several overflow or Jet units or funnels arranged in series, through which the cord fabric is passed while tied into a ring. The fabric is subdivided by the number of Overflow or Jet units or funnels constituting the machine and is capable of passing several Overflow or Jet units or funnels in sequence, as many times as needed to dye the fabric, while constantly maintaining the fabric's subdivision.
In particular, in the machine according to the '474 application, the speed of the reels of each Overflow or Jet unit or funnel is syncronized with respect to that of a pilot reel, while slippages of the fabric in any other reel are corrected by a controlling system on the machine, for example in the form of a microprocessor. This synchronization is possible thanks to the fact that the fabric to be dyed is subdivided in as many equal parts as the Overflow or Jet units or funnels constituting the machine, and a magnet is positioned on at least one of these Overflow or Jet units or funnels. An appropriate sensor is provided to signal the passage of the magnet to the microprocessor and to take action to retard or advance the affected reel.
Such a machine, while still operating extremely well in its overall concept, provides, as already mentioned, for passing the fabric from reel to reel in a sequence, from the first to the last and then returning it through a long conduit from the last reel back to the first reel.
In practical terms, this kind of transport of the fabric puts a restriction on the fabric's moving speed, to the point of preventing adequate processing.
The head losses in such a long return conduit limit, due to the fabric's friction on the inner conduit surface, the circulating speed of the piece of fabric, even in a machine equipped with two treating compartments.
These problems relating to the circulation of the piece of fabric are increased out of all proportion in a machine involving several compartments, for instance four or six. In this case, the speed limitation becomes unsustainable and the machine quits working in an industrially acceptable way.